Photocurable liquid resin composition

ABSTRACT

The present invention relates to a photocurable liquid resin composition comprising: (A) a cationically polymerizable organic compound; (B) a cationic photopolymerization initiator; (C) an ethylenically unsaturated monomer; (D) a radical photopolymerization initiator; (E) a polyether polyol compound having one or more hydroxyl groups in one molecule; and, optionally, includes elastomer particles having a specific particle diameter and/or an epoxy-branched alicyclic compound.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The contents of Japanese Application No. JP 98-52729, filed Feb.18, 1998;Japanese Applications No. JP 98-58861, and JP 98-58862, bothfiled Feb. 24, 1998; and Japanese Application JP 98-62090, filed Feb.26, 1999 are hereby incorporated in their entirety by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to a photocurable liquid resincomposition exhibiting superior photocurability and capable of producinga cured product exhibiting high mechanical strength. More particularly,the present invention relates to a photocurable resin compositionsuitably used as a coating material for plastics, various films, wood,ceramic wares, glass, quartz fibers for optical communication, papers,metals, cans for drinks, fibers, and the like, a resin forphotofabrication of three-dimensional objects, sealing materials oradhesives for semi-conductor devices, under fill materials, adhesivesfor optical materials, printing board materials, and the like. Inparticular, when said composition is used as a resin forphotofabrication of three-dimensional objects, the composition exhibitshigh photocurability by exposure to various light sources such as alaser and an UV lamp, and the resulting cured three-dimensional objectsexhibit excellent impact resistance and superior folding endurance.

BACKGROUND OF THE INVENTION

[0003] In recent years, photofabrication of three-dimensional objectsconsisting of cured resin layers integrally laminated by repeating astep of selectively irradiating a photocurable liquid material(photocurable resin composition) has been proposed (see Japanese PatentApplications Laid-open No. 247515/1985, U.S. Pat. No. 4,575,330, No.35966/1987, No. 101408/1987, and No. 24119/1993).

[0004] A typical example of the above photofabrication process is asfollows. A cured resin layer having a specified pattern is formed byselective exposure to radiation such as from an ultraviolet laser on thesurface of the photocurable resin composition in a vessel. An amount ofthe photocurable resin composition equivalent to another layer is thenprovided over this cured resin layer followed by selective irradiationto the liquid surface to form a new cured resin layer integrallylaminated over the primary layer. The above step using the same ordifferent irradiated patterns is repeated certain times to obtain athree-dimensional object consisting of a plural integrally-laminatedcured resin layer. This photofabrication process has attractedconsiderable attention, since three-dimensional objects having acomplicated shape can be easily formed in a short time by using thisprocess.

[0005] As the photocurable resin composition used in thisphotofabrication of three-dimensional objects, the following resincompositions (a) to (c) have been conventionally proposed:

[0006] (a) a resin composition containing a radically polymerizableorganic compound such as urethane (meth)acrylate, oligoester(meth)acrylate, epoxy (meth)acrylate, thiol, ene compound, andphotosensitive polyimide (see, for example, Japanese Patent ApplicationsLaid-open No. 204915/1989, No. 208305/1990, and No. 160013/1991);

[0007] (b) a resin composition containing a cationically polymerizableorganic compound such as an epoxy compound, cyclic ether compound,cyclic lactone compound, cyclic acetal compound, cyclic thioethercompound, spiro orthoester compound, and vinyl ether compound (see, forexample, Japanese Patent Application Laid-open No. 213304/1989); and

[0008] (c) a resin composition containing both a radically polymerizableorganic compound and a cationically polymerizable organic compound (see,for example, Japanese Patent Applications Laid-open No. 28261/1990, No.75618/1990, and No. 228413/1994).

[0009] In view of efficiency of the photofabrication, the photocurableresin composition used in the photofabrication is required to exhibitlow viscosity for immediately forming a smooth liquid surface and highcurability by exposure to radiation, and the resulting cured productconsisting of the three-dimensional objects is required to exhibit noswelling and minimal deformation such as warping, indentation, andoverhanging of the stretched part caused by shrinkage during curing byexposure to radiation. Moreover, superior stability with time of thesemechanical properties are required for such objects.

[0010] The three-dimensional objects formed by the photofabrication areused for design models, prototypes of mechanical parts, and the like. Inparticular, when these three-dimensional objects are used for prototypesof mechanical parts, such objects have to be formed by high-precisionmicrofabrication conforming to specified procedures and exhibitsufficient mechanical strength, superior heat resistance, and excellentwaterproofing characteristics under use conditions.

[0011] However, no conventional resin composition can satisfy the abovedemands. Three-dimensional objects formed by photofabricating theabove-described conventional resin compositions exhibited deformationwith time such as warping, indentation, and overhanging of the stretchedpart due to residual distortion caused by the shrinkage during curing.When the resin composition (a) containing a radically polymerizableorganic compound such as urethane (meth)acrylate, oligoester(meth)acrylate, epoxy (meth)acrylate, thiol, ene compound, andphotosensitive polyimide is used as the photocurable resin, although theresulting three-dimensional objects exhibit relatively excellentmechanical properties, it has been pointed out that further improvementsare required to minimize inaccuracy of fabrication and variation withtime of the fabricated forms (Journal of Fabrication, vol. 9, No. 5, pp.330-335, 1997). In order to increase accuracy of fabrication, a methodfor controlling phototransmission depth of the resin composition byblending core-shell composite polymer particles (see Japanese PatentApplication Laid-open No. 114733/1991) or particles consisting ofpolarizing materials having a refractive index essentially differingfrom that of the resin composition (see Japanese Patent ApplicationLaid-open No. 103415/1991) by utilizing diffusion of light has beenproposed. However, sufficient accuracy of fabrication has not beenachieved by using such a method.

[0012] When the resin composition (b) containing a cationicallypolymerizable organic compound such as an epoxy compound, cyclic ethercompound, cyclic lactone compound, cyclic acetal compound, cyclicthioether compound, spiro orthoester compound, and vinyl ether compoundis used as the photocurable resin, fabrication cannot be carried outefficiently due to insufficient curablity of the composition. Thethree-dimensional objects formed from the resin composition (b) exhibitrelatively higher accuracy of fabrication. However, because mechanicalproperties of the resulting three-dimensional objects deteriorate withtime depending on the working conditions (temperature and humidity),such objects cannot be used under the conditions where long-termmechanical strength is required. Moreover, it has been pointed out thatthese objects cannot be used practically as functional parts because ofinsufficient mechanical strength, in particular, insufficient toughnesssuch as low impact resistance and low folding endurance.

[0013] In view of the above situation, the resin composition (c)containing both a radically polymerizable organic compound and acationically polymerizable organic compound has been proposed. Althoughcurability of the composition is improved to a certain extent, theobjects formed from the composition cannot be used in practice becauseof inadequate mechanical properties, in particular, insufficienttoughness.

[0014] In order to provide three-dimensional objects with mechanicalstrength, toughness in particular, a resin composition containingmicroparticles with a specific gravity differing from that of the resincomposition in a range within 0.2 has been proposed (see Japanese PatentApplication Laid-open No. 145616/1990). In spite of increased toughnessof the resulting three-dimensional objects, such objects exhibited weakfolding endurance during repeated foldings when used as functionalparts.

[0015] The present invention has been achieved based on the abovesituation.

[0016] An object of the present invention is to provide a novelphotocurable liquid resin composition.

[0017] A second object of the present invention is to provide aphotocurable liquid resin composition used for photofabrication ofthree-dimensional objects which exhibit superior mechanical strength andhigh dimensional accuracy and are suitably used as prototypes formechanical parts and the like.

[0018] A third object of the present invention is to provide aphotocurable liquid resin composition used for photofabrication ofthree-dimensional objects exhibiting small deformation with time.

[0019] A fourth object of the present invention is to provide aphotocurable liquid resin composition used for photofabrication ofthree-dimensional objects exhibiting small variation of mechanicalproperties with time.

[0020] A fifth object of the present invention is to provide aphotocurable liquid resin composition used for photofabrication ofthree-dimensional objects exhibiting superior mechanical properties, inparticular, high toughness such as high impact resistance.

[0021] A sixth object of the present invention is to provide aphotocurable liquid resin composition used for photofabrication ofthree-dimensional objects exhibiting high folding endurance.

[0022] A further object of the present invention includes those whereinthe photofabrication composition is transparent before cure and/or aftercure.

SUMMARY OF THE INVENTION

[0023] The above objects can be achieved by the photocurable liquidresin composition of the present invention comprising:

[0024] (A) a cationically polymerizable organic compound;

[0025] (B) a cationic photopolymerization initiator;

[0026] (C) an ethylenically unsaturated monomer;

[0027] (D) a radical photopolymerization initiator;and

[0028] (E) a polyether polyol compound having one or more hydroxylgroups in one molecule.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029]FIG. 1 is a perspective view of a a three-dimensional model usedfor measuring the deformation with respect to time of the cured productsformed from the photocurable compositions of Examples and ComparativeExamples.

[0030]FIG. 2 is an elevation view of the three-dimensional model, ofFIG. 1, in the for measuring accuracy of fabrication (dimension) of thecured products formed from the photocurable compositions of Examples andComparative Examples.

[0031]FIG. 3 is an elevation view of a three-dimensional object used formeasuring dimensional accuracy of the cured products formed from thephotocurable compositions of Examples and Comparative Examples.

EXPLANATION OF SYMBOLS IN FIG. 2.

[0032]10: warping model

[0033]11, 12: leg

[0034]20: horizontal stand

Cationically Polymerizable Organic Compound (A)

[0035] The cationically polymerizable organic compound (A) of thephotocurable resin composition of the present invention (herein alsocalled “component (A)”) polymerizes or crosslinks by irradiation in thepresence of cationic photopolymerization initiators.

[0036] The molecular weight of component (A) is between 120 and 10,000,preferably between 150 and 5,000, more preferably between 180 and 2,000.

[0037] Examples of such a compound include epoxy compounds, oxetanecompounds, oxolane compounds, cyclic acetal compounds, cyclic lactonecompounds, thiirane compounds, thiethane compounds, vinyl ethercompounds, spiro orthoester compounds obtained by the reaction of anepoxy compound with at least one lactone compound, ethylenicallyunsaturated compound, cyclic ether compound, cyclic thioether compound,vinyl compound, and/or the like.

[0038] Preferred cationically polymerizable organic compounds includeglycidyl ether compounds, including di-, tri- and polyglycidyl ethercompounds, and alicyclic ether compounds including those comprisingresidue of carboxylic acids such as, for example, alkylcarboxylic acidresidual groups, alkylcycloalkylcarboxylic acid residual groups anddialkyl dicarboxylic acid residual groups. Suitable epoxy compounds thatcan be used as component (A) include, for example, bisphenol Adiglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidylether, brominated bisphenol A diglycidyl ether, brominated bisphenol Fdiglycidyl ether, brominated bisphenol S diglycidyl ether, epoxy novolakresin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenolF diglycidyl ether, hydrogenated bisphenol S diglycidyl ether,3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate,2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-1,4-dioxane,bis(3,4-epoxycyclohexylmethyl)adipate, vinylcyclohexene oxide,4-vinylepoxycyclohexane,bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate,3,4-epoxy-6-methylcyclohexyl-3′,4′-epoxy-6′-methylcyclohexanecarboxylate,methylenebis(3,4-epoxycyclohexane), dicyclopentadiene diepoxide,di(3,4-epoxycyclohexylmethyl)ether of ethylene glycol,ethylenebis(3,4-epoxycyclohexanecarboxylate),epoxyhexahydrodioctylphthalate, epoxyhexahydro-di-2-ethylhexylphthalate, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidylether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether,polyethylene glycol diglycidyl ether, polypropylene glycol diglycidylether, polyglycidyl ethers of polyether polyol obtained by the additionof one or more alkylene oxides to aliphatic polyhydric alcohols such asethylene glycol, propylene glycol, and glycerol, diglycidyl esters ofaliphatic long-chain dibasic acids, monoglycidyl ethers of aliphatichigher alcohols, monoglycidyl ethers of phenol, cresol, butyl phenol, orpolyether alcohols obtained by the addition of alkylene oxide to thesecompounds, glycidyl esters of higher fatty acids, epoxidated soybeanoil, epoxybutylstearic acid, epoxyoctylstearic acid, epoxidated linseedoil, epoxidated polybutadiene, and the like can be given.

[0039] Examples of other cationically polymerizable organic compoundswhich can be used as the component (A) include oxetanes such astrimethylene oxide, 3,3-dimethyloxetane, 3,3-dichloromethyloxetane,3-ethyl-3-phenoxymethyloxetane, and bis(3-ethyl-3-methyloxy)butane;oxolanes such as tetrahydrofuran and 2,3-dimethyltetrahydrofuran; cyclicacetals such as trioxane, 1,3-dioxolane, and 1,3,6-trioxanecyclooctane;cyclic lactones such as β-propyolactone and ε-caprolactone; thiiranessuch as ethylene sulfide, 1,2-propylene sulfide, andthioepichlorohydrin; thiethanes such as 3,3-dimethylthiethane; vinylethers such as ethylene glycol divinyl ether, triethylene glycol divinylether, trimethylolpropane trivinyl ether; spiro orthoesters obtained bythe reaction of an epoxy compound and lactone; ethylenically unsaturatedcompounds such as vinylcyclohexane, isobutylene, and polybutadiene;derivatives of the above compounds; and the like.

[0040] Of these cationically polymerizable organic compounds, bisphenolA diglycidyl ether, bisphenol F diglycidyl ether, hydrogenated bisphenolA diglycidyl ether, hydrogenated bisphenol F diglycidyl ether,3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate,bis(3,4-epoxycyclohexylmethyl)adipate, 1,4-butanediol diglycidyl ether,1,6-hexanediol diglycidyl ether, glycerol triglycidyl ether,trimethylolpropane triglycidyl ether, neopentyl glycol diglycidyl ether,polyethylene glycol diglycidyl ether, and polypropylene glycoldiglycidyl ether are preferable.

[0041] As even more preferred cationically polymerizable organiccompounds used as the component (A), epoxy compounds having two or morealicyclic epoxy groups in a molecule such as3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate, andbis(3,4-epoxycyclohexylmethyl)adipate can be given.

[0042] As examples of commercially available products of thecationically polymerizable organic compounds suitably used as thecomponent (A), UVR-6100, UVR-6105, UVR-6110, UVR-6128, UVR-6200,UVR-6216 (manufactured by Union Carbide Corp.), Celoxide 2021, Celoxide2021P, Celoxide 2081, Celoxide 2083, Celoxide 2085, Celoxide 2000,Celoxide 3000, Glycidole, AOEX 24, Cyclomer A200, Cyclomer M100, EpoleadGT-300, Epolead GT-301, Epolead GT-302, Epolead GT-400, Epolead 401,Epolead 403 (manufactured by Daicel Chemical Industries, Ltd.), Epicoat828, Epicoat 812, Epicoat 1031, Epicoat 872, Epicoat CT508 (manufacturedby Yuka-Shell Epoxy K.K.), KRM-2100, KRM-2110, KRM-2199, KRM-2400,KRM-2410, KRM-2408, KRM-2490, KRM-2200, KRM-2720, KRM-2750 (manufacturedby Asahi Denka Kogyo Co., Ltd.), Rapi-Cure DVE-3, CHVE, PEPC(manufactured by ISP), VECTOMER 2010, 2020, 4010, 4020 (manufactured byAlliedSignal), and the like can be given.

[0043] Component (A) may comprise a single type of cationicallypolymerizable compound or include combinations of two or morecationically polymerizable compounds.

[0044] The proportion of the component (A) used in the photocurableresin composition of the present invention is usually, relative to thetotal compositon, 20-85 wt %, preferably 30-80 wt %, and more preferably40-75 wt %. If the proportion is too small, three-dimensional objectsformed from the resin composition may exhibit insufficient dimensionalaccuracy and deformation with time may be caused. On the other hand, ifthe proportion is too large, the resin composition may exhibit inferiorphotocurability which may result in inefficient fabrication.

Cationic Photopolymerization Initiator (B)

[0045] The cationic photopolymerization initiator of the photocurableresin composition of the present invention (herein also called“component (B)”) evolves a material which initiates cationicallypolymerization of the component (A) by exposure to energy rays such asradiation. Here, energy rays such as radiation include visible rays,ultraviolet rays, infrared rays, X-ray, α-rays, β-rays, γ-rays, and thelike. As examples of preferable compounds used as the component (B),onium salts represented by formula (1) can be given:

[R¹ _(a)R² _(b)R³ _(c)R⁴ _(d)W]^(+m)[MX_(n+m)]  (I)

[0046] wherein a cation is an onium ion; W represents S, Se, Te, P, As,Sb, Bi, O, I, Br, Cl, or —N≡βN; R¹, R², R³, and R⁴ independentlyrepresent organic groups; a, b, c, and d independently representintegers from 0-3, provided that the total of (a+b+c+d) is equal to theof valence of W; M is a metal or a metalloid which constitutes a centeratom of the halide complex [MX_(n+m)] for example, M represents B, P,As, Sb, Fe, Sn, Bi, Al, Ca, In, Ti, Zn, Sc, V, Cr, Mn, Co; X representsa halogen atom such as F, Cl, and Br; m represents a positive charge ofa halide complex ion; and n represents a valence of M. This onium saltevolves Lewis acids by irradiation.

[0047] As specific examples of an anion [MX_(n+m)] in the above formula(1), tetrafluoroborate (BF₄ ⁻), hexafluorophosphate (PF₆ ⁻),hexafluoroantimonate (SbF₆ ⁻), hexafluoroarsenate (AsF₆ ⁻),hexachloroantimonate (SbCl₆ ⁻), and the like can be given.

[0048] Moreover, onium salts having an anion represented by the formula[MX_(n)(OH)⁻] and onium salts having other anions such as perchloricacid ion (ClO₄ ⁻), trifluoromethane sulfonic acid ion (CF₃SO₃ ⁻),fluorosulfonic acid ion (FSO₃ ⁻), toluenesulfonic acid ion,trinitrobenzenesulfonic acid anion, trinitrotoluenesulfonic acid anioncan also be used.

[0049] Of these onium salts, aromatic onium salts are more preferable asthe component (B). Examples of such aromatic onium salts include:aromatic halonium salts disclosed in, for example, Japanese PatentApplications Laid-open No. 151996/1975 and No. 158680/1975, VIA grouparomatic onium salts disclosed in, for example, Japanese PatentApplications Laid-open No. 151997/1975, No. 30899/1977, No. 55420/1981,and No. 125105/1980; VA group aromatic onium salts disclosed in, forexample, Japanese Patent Application Laid-open No. 158698/1975;oxosulfoxonium salts disclosed in, for example, Japanese PatentApplications Laid-open No. 8428/1981, No. 149402/1981, and No.192429/1982; aromatic diazonium salts disclosed in, for example,Japanese Patent Application Laid-open No. 17040/1974; thiopyrylium saltsdisclosed in, for example, U.S. Pat. No. 4,139,655; and the like. Inaddition, iron/allene complex initiators, aluminum complex/photolysissilicon compound initiators, and the like can also be given as examples.

[0050] As examples of commercially available products of cationicphotopolymerization initiators suitably used as the component (B),UVI-6950, UVI-6970, UVI-6974, UVI-6990 (manufactured by Union CarbideCorp.), Adekaoptomer SP-150, SP-151, SP-170, SP-171 (manufactured byAsahi Denka Kogyo Co., Ltd.), Irgacure 261 (manufactured by CibaSpecialty Chemicals Co., Ltd.), CI-2481, CI-2624, CI-2639, CI-2064(manufactured by Nippon Soda Co., Ltd.), CD-1010, CD-1011, CD-1012(manufactured by Sartomer Co., Ltd.), DTS-102, DTS-103, NAT-103,NDS-103, TPS-103, MDS-103, MPI-103, BBI-103 (manufactured by MidoriChemical Co., Ltd.), PCI-061T, PCI-062T, PCI-020T, PCI-022T(manufactured by Nippon Kayaku Co., Ltd.), and the like can be given. Ofthese, UVI-6970, UVI-6974, Adekaoptomer SP-170, SP-171, CD-1012, andMPI-103 are particularly preferable in view of higher photocuringsensitivity of the resulting resin composition.

[0051] These cationic photopolymerization initiators can be used eitherindividually or in combinations of two or more as the component (B).

[0052] The proportion of the component (B) used in the photocurableresin composition of the present invention is usually, relative to thetotal weight of the composition, 0.1-10 wt %, preferably 0.2-5 wt %, andmore preferably 0.3-3 wt %. If the proportion of the component (B) istoo small, decreased photocurablility of the resin composition mayresult in insufficient mechanical strength of the resultingthree-dimensional objects. On the other hand, if the proportion is toolarge, controlling of cure depth of the resin composition may bedifficult due to insufficient phototransmission in the photofabrication,whereby the resulting three-dimensional objects may exhibit insufficientaccuracy of fabrication.

Ethylenically Unsaturated Monomer (C)

[0053] The ethylenically unsaturated monomer (C) of the photocurableresin composition of the present invention (herein also called“component (C)”) is a compound having an ethylenically unsaturated bond(C═C) in the molecule. Examples of such a compound includemonofunctional monomers having one ethylenically unsaturated bond in onemolecule and polyfunctional monomers having two or more ethylenicallyunsaturated bonds in one molecule.

[0054] The molecular weight of the ethylenically unsaturated monomer (c)is between 80-10,000, preferably between 100-5,000, more preferablybetween 110-2,000.

[0055] As examples of monofunctional monomers which can be suitably usedas the component (C), acrylamide, (meth)acryloylmorpholine,7-amino-3,7-dimethyloctyl (meth)acrylate, isobutoxymethyl(meth)acrylamide, isobornyloxyethyl (meth)acrylate, isobornyl(meth)acrylate, 2-ethylhexyl (meth)acrylate, ethyldiethylene glycol(meth)acrylate, t-octyl (meth)acrylamide, diacetone (meth)acrylamide,dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate,lauryl (meth)acrylate, dicyclopentadiene (meth)acrylate,dicyclopentenyloxyethyl (meth)acrylate, dicyclopentenyl (meth)acrylate,N,N-dimethyl(meth)acrylamidetetrachlorophenyl (meth)acrylate,2-tetrachlorophenoxyethyl (meth)acrylate, tetrahydrofurfuryl(meth)acrylate, tetrabromophenyl (meth)acrylate,2-tetrabromophenoxyethyl (meth)acrylate, 2-trichlorophenoxyethyl(meth)acrylate, tribromophenyl (meth)acrylate, 2-tribromophenoxyethyl(meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl(meth)acrylate, vinylcaprolactam, N-vinylpyrrolidone, phenoxyethyl(meth)acrylate, butoxyethyl (meth)acrylate, pentachlorophenyl(meth)acrylate, pentabromophenyl (meth)acrylate, polyethylene glycolmono(meth)acrylate, polypropylene glycol mono(meth)acrylate, bornyl(meth)acrylate, methyltriethylene diglycol (meth)acrylate, alkoxylatedphenol(meth)acrylate, alkoxylated alkyl phenol(meth)acrylate, esterifiedmethyltetrahydrofuran (meth)acrylate, esterified2-isobutoxyl-1,3-dioxane(meth)acrylate, and esterifiedmethylated-2-isobutoxyl-1,3-dioxane(meth)acrylate.

[0056] Of these monofunctional monomers, isobornyl (meth)acrylate,lauryl (meth)acrylate, and phenoxyethyl (meth)acrylate are particularlypreferable.

[0057] As examples of commercially available products of thesemonofunctional monomers, ARONIX M-101, M-102, M-111, M-113, M-117,M-152, TO-1210 (manufactured by Toagosei Co., Ltd.), KAYARAD TC-110S,R-564, R-128H (manufactured by Nippon Kayaku Co., Ltd.), Viscoat 192,220, 2311HP, 2000, 2100, 2150, 8F, 17F (manufactured by Osaka OrganicChemical Industry Co., Ltd.), and the like can be given.

[0058] Polyfunctional monomers may include those derived frompolyalcohols having 3-8 hydroxy groups. Preferably, the polyfunctionalmonomers are derived from polyalcohols such as pentaerythritols(including di-pentaerythritol) and trialkylolalkaans. The polyalcoholsmay be reacted with a lactone, for example, caprolactone and the like;and/or alkoxylated with 1-12 moles of an alkoxide including, forexample, etheneoxide or propeneoxide. Examples of polyfunctionalmonomers which can be suitably used as the component (C) includeethylene glycol di(meth)acrylate, dicyclopentenyl di(meth)acrylate,triethylene glycol diacrylate, tetraethylene glycol di(meth)acrylate,tricyclodecanediyldimethylene di(meth)acrylate,tris(2-hydroxyethyl)isocyanurate di(meth)acrylate,tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate,caprolactone-modified tris(2-hydroxyethyl)isocyanuratetri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide(hereinafter called “EO”) modified trimethylolpropane tri(meth)acrylate,propylene oxide (hereinafter called “PO”) modified trimethylolpropanetri(meth)acrylate, tripropylene glycol di(meth)acrylate, neopentylglycol di(meth)acrylate, bisphenol A diglycidyl ether with both terminal(meth)acrylates, 1,4-butanediol di(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritoltetra(meth)acrylate, polyester di(meth)acrylate, polyethylene glycoldi(meth)acrylate, dipentaerythritol hexa(meth)acrylate,dipentaerythritol penta(meth)acrylate, dipentaerythritoltetra(meth)acrylate, caprolactone-modified dipentaerythritolhexa(meth)acrylate, caprolactone-modified dipentaerythritolpenta(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate,EO-modified bisphenol A di(meth)acrylate, PO-modified bisphenol Adi(meth)acrylate, EO-modified hydrogenated bisphenol A di(meth)acrylate,PO-modified hydrogenated bisphenol A di(meth)acrylate, EO-modifiedbisphenol F di(meth)acrylate, (meth)acrylate of phenol novolakpolyglycidyl ether, and the like.

[0059] As examples of commercially available products of thesepolyfunctional monomers, SA1002 (manufactured by Mitsubishi ChemicalCorp.), Viscoat 195, 230, 260, 215, 310, 214HP, 295, 300, 360, GPT, 400,700, 540, 3000, 3700 (manufactured by Osaka Organic Chemical IndustryCo., Ltd.), KAYARAD R-526, HDDA, NPGDA, TPGDA, MANDA, R-551, R-712,R-604, R-684, PET-30, GPO-303, TMPTA, THE-330, DPHA, DPHA-2H, DPHA-2C,DPHA-2I, D-310, D-330, DPCA-20, DPCA-30, DPCA-60, DPCA-120, DN-0075,DN-2475, T-1420, T-2020, T-2040, TPA-320, TPA-330, RP-1040, RP-2040,R-011, R-300, R-205 (manufactured by Nippon Kayaku Co., Ltd.), ARONIXM-210, M-220, M-233, M-240, M-215, M-305, M-309, M-310, M-315, M-325,M-400, M-6200, M-6400 (manufactured by Toagosei Co., Ltd.), LiteAcrylate BP-4EA, BP-4PA, BP-2EA, BP-2PA, DCP-A (manufactured by KyoeishaChemical Co., Ltd.), New Frontier BPE-4, BR-42M, GX-8345 (manufacturedby Daiichi Kogyo Seiyaku Co., Ltd.), ASF-400 (manufactured by NipponSteel Chemical Co., Ltd.), Lipoxy SP-1506, SP-1507, SP-1509, VR-77,SP-4010, SP-4060 (manufactured by Showa Highpolymer Co., Ltd.), NK EsterA-BPE-4 (manufactured by Shin-Nakamura Chemical Co., Ltd.), and the likecan be given.

[0060] The above monofunctional monomers and polyfunctional monomers canbe used either individually or in combinations of two or more, or incombinations of at least one monofunctional monomer and at least onepolyfunctional monomer as the component (C). It is preferable that thecomponent (C) contain 60 wt % of polyfunctional monomers having three ormore ethylenically unsaturated bonds in a molecule. The proportion ofthese polyfunctional monomers having three or more ethylenicallyunsaturated bonds used in the component (C) is more preferably 70 wt %or more, even more preferably 80 wt % or more, and most preferably 100wt %. If the proportion of these polyfunctional monomers is less than 60wt %, the resin composition may exhibit decreased photocurability andthe resulting three-dimensional objects may exhibit deformation withtime.

[0061] These polyfunctional monomers having three or more ethylenicallyunsaturated bonds can be selected from the group consisting of theabove-mentioned tri(meth)acrylate compounds, tetra(meth)acrylatecompounds, penta(meth)acrylate compounds, and hexa(meth)acrylatecompounds. Of these, trimethylolpropane tri(meth)acrylate, EO-modifiedtrimethylolpropane tri(meth)acrylate, dipentaerythritolhexa(meth)acrylate, dipentaerythritol penta(meth)acrylate,ditrimethylolpropane and tetra(meth)acrylate are particularlypreferable.

[0062] The proportion of the component (C) used in the photocurableresin composition of the present invention is usually, relative to thetotal composition, 5-45 wt %, preferably 7-35 wt %, and more preferably7-25 wt %. If the proportion of the component (C) is too small,insufficient photocurability of the resin composition may result ininferior mechanical strength of the three-dimensional objects. On theother hand, if the proportion is too large, the resin composition mayexhibit shrinkage during curing by irradiation and the resultingthree-dimensional objects may exhibit insufficient heat resistance anddecreased moisture resistance.

Radical Photopolymerization Initiator (D)

[0063] The radical photopolymerization initiator (D) of the photocurableresin composition of the present invention (herein also called“component (D)”) is a compound which decomposes by exposure to energyrays such as radiation to initiate radical polymerization of thecomponent (C) with radicals.

[0064] As specific examples of the radical photopolymerization initiatorused as the component (D), acetophenone, acetophenone benzyl ketal,anthraquinone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one,carbazole, xanthone, 4-chlorobenzophenone, 4,4′-diaminobenzophenone,1,1-dimethoxydeoxybenzoin, 3,3′-dimethyl-4-methoxybenzophenone,thioxanethone compounds,2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-2-on,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one,triphenylamine, 2,4,6-trimethylbenzoyldiphenylphosphine oxide,bis(2,6-dimethoxybenzoyl-2,4,4-trimethylpentylphosphine oxide, benzyldimethyl ketal, 1-hydroxycyclohexylphenyl ketone,2-hydroxy-2-methyl-1-phenylpropan-1-one, fluorenone, fluorene,benzaldehyde, benzoin ethyl ether, benzoin propyl ether, benzophenone,Michler's ketone, 3-methylacetophenone,3,3′,4,4′-tetra(t-butylperoxycarbonyl)benzophenone (BTTB), combinationsof BTTB and dyesensitizers such as xanthene, thioxanthene, cumarin, andketocumarin, and the like can be given. Of these, benzyl dimethyl ketal,1-hydroxycyclohexylphenyl ketone,2,4,6-trimethylbenzoyldiphenylphosphine oxide,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, and thelike are particularly preferable.

[0065] These radical photopolymerization initiators can be used eitherindividually or in combinations of two or more as the component (D).

[0066] The proportion of the component (D) used in the photocurableresin composition of the present invention is usually, relative to thetotal composition, 0.01-10 wt %, and preferably 0.1-8 wt %. If theproportion is too small, the radical polymerization rate (cure rate) ofthe resin composition may be lower, whereby fabrication may require alonger processing time or resolution may be decreased. On the otherhand, if the proportion is too large, curing properties of the resincomposition may be impaired or moisture resistance and heat resistanceof the resulting three-dimensional objects may be adversely affected byexcess polymerization initiator.

[0067] Polyol (E)

[0068] The polyol having three or more hydroxyl groups is a componentfor developing the photo-curability of the resin composition (hereinalso called “component (E)”). The polyol provides assistance to thethree-dimensional object to prevent deformation over time (i.e., shapestability) and resistance to change in mechanical characteristics overtime (i.e., physical property stability). (over time). Preferably, thepolyol used as component (E) has three or more, preferably 3-6 hydroxylgroups. If polyols having less than three hydroxyl groups (i.e., diol)are used, photo-curing characteristics can not be attained and theresulting three-dimensional object lacks the desired mechanicalstrength. On the other hand, if polyols having more than six hydroxylgroups are used, the elongation and toughness of the resultingthree-dimensional object tends to be lower.

[0069] Preferred examples of compounds useful as component (E) includepolyether polyols having three or more, and preferably from 3 to 6hydroxyl groups in a molecule. Use of polyether polyols having less thanthree hydroxyl groups in a molecule (polyether diol) may result ininsufficient photocurability of the resin composition and decreasedmechanical properties, in particular, low modulus of elasticity of theresulting three-dimensional objects. On the other hand, if polyetherpolyols having more than six hydroxyl groups in a molecule are used, theresulting three-dimensional objects may exhibit insufficient elongationand decreased moisture resistance.

[0070] As examples of the component (E), polyether polyols obtained bymodifying polyhydric alcohols having more than three hydroxyl groupssuch as trimethylolpropane, glycerol, pentaerythritol, sorbitol,sucrose, and quadrol with cyclic ether compounds such as ethylene oxide(EO), propylene oxide (PO), butylene oxide, and tetrahydrofuran can begiven. Specific examples include EO-modified trimethylolpropane,PO-modified trimethylolpropane, tetrahydrofuran-modifiedtrimethylolpropane, EO-modified glycerol, PO-modified glycerol,tetrahydrofuran-modified glycerol, EO-modified pentaerythritol,PO-modified pentaerythritol, tetrahydrofuran-modified pentaerythritol,EO-modified sorbitol, PO-modified sorbitol, EO-modified sucrose,PO-modified sucrose, EO-modified sucrose, EO-modified quadrol and thelike. Of these, EO-modified trimethylolpropane, PO-modifiedtrimethylolpropane, PO-modified glycerol, PO-modified sorbitol arepreferable as the component (E).

[0071] The molecular weight of the polyether polyol (E) is preferably100-2,000, and more preferably 160-1,000. If the molecular weight of thepolyether polyol (E) is too small, form stability and physical stabilityof three-dimensional objects formed from the resin composition may beinsufficient. On the other hand, if the molecular weight of thepolyether polyol (E) is too large, increased viscosity of the resincomposition may give rise to lower modulus of elasticity of thethree-dimensional objects formed by photofabrication.

[0072] As examples of commercially available products of polyetherpolyols used as the component (E), Sunnix TP-400, GP-600, GP-1000,SP-750, GP-250, GP-400, GP-600 (manufactured by Sanyo ChemicalIndustries, Ltd.), TMP-3 Glycol, PNT-4 Glycol, EDA-P-4, EDA-P-8(manufactured by Nippon Nyukazai Co., Ltd.), G-300, G-400, G-700, T-400,EDP-450, SP-600, SC-800 (manufactured by Asahi Denka Kogyo Co., Ltd.),and the like can be given.

[0073] These polyether polyols can be used either individually or incombinations of two or more as the component (E).

[0074] The proportion of the component (E) used in the photocurableresin composition of the present invention is usually, relative to thetotal composition, 5-35 wt %, preferably 7-30 wt %, and more preferably10-25 wt %. If the proportion is too small, insufficient photocurabilityof the resin composition may result in decreased form stability anddecreased physical stability of the resulting three-dimensional objects.On the other hand, if the proportion is too large, insufficientphotocurability of the resin composition may give rise to lower modulusof elasticity for the resulting three-dimensional objects.

(Optionally) Elastomer Particles (F) Having an Average Particle Diameterof 10-700 nm

[0075] The photocurable resin compositions of the present invention mayoptionally employ elastomer particles (herein referred to as “component(F)” or “particles (F)”). The elastomer particles (F) having an averageparticle diameter of 10-700 nm used for the photocurable resincomposition of the present invention include elastomer particles such aspolybutadiene, polyisoprene, butadiene/acrylonitrile copolymer,styrene/butadiene copolymer, styrene/isoprene copolymer,ethylene/propylene copolymer, ethylene/α-olefin copolymer,ethylene/α-olefin/polyene copolymer, acrylic rubber,butadiene/(meth)acrylate copolymer, styrene/butadiene block copolymer,and styrene/isoprene block copolymer, and core-shell particles obtainedby coating these elastomer particles with methyl methacrylate polymer,methyl methacrylate/glycidyl methacrylate copolymer, and the like.Crosslinking structures may be introduced into these elastomer particlesby using a commonly used method. As examples of crosslinking agents usedin such a method, divinylbenzene, ethylene glycol di(meth)acrylate,diallylmaleate, triallylcyanurate, triallylisocyanurate,diallylphthalate, trimethylolpropane triacrylate, allyl methacrylate,and the like can be given.

[0076] Suitable elastomer particles suitably useful as component (F)include, for example, elastomer particles containing polybutadiene,polyisoprene, styrene/butadiene copolymer, styrene/isoprene copolymer,ethylene/propylene copolymer, ethylene/α-olefin copolymer,ethylene/α-olefin/polyene copolymer, acrylic rubber,butadiene/(meth)acrylate copolymer, styrene/butadiene block copolymer,and styrene/isoprene block copolymer as a base component.

[0077] Suitable elastomer particles of the the core-shell type include,for example, elastomer particles in which a partially crosslinked coreof polybutadiene, polyisoprene, styrene/butadiene copolymer,styrene/isoprene copolymer, ethylene/propylene copolymer,ethylene/α-olefin copolymer, ethylene/α-olefin/polyene copolymer,acrylic rubber, butadiene/(meth)acrylate copolymer, styrene/butadieneblock copolymer, styrene/isoprene block copolymer, and the like iscoated with methyl methacrylate polymer, methyl methacrylate/glycidylmethacrylate copolymer, and the like. A ratio of a core radius to ashell thickness of the core-shell composite particles is usually from1/2 to 1000/1, preferably from 1/1 to 200/1 (for example, if the coreradius is 350 nm and the shell thickness is 10 nm, the ratio isexpressed as 35/1).

[0078] Of these elastomer particles, elastomer particles in which apartially crosslinked core of polybutadiene, polyisoprene,styrene/butadiene copolymer, styrene/isoprene copolymer,butadiene/(meth)acrylate copolymer, styrene/butadiene block copolymer,and styrene/isoprene block copolymer is coated with methyl methacrylatepolymer, methyl methacrylate/glycidyl methacrylate copolymer areparticularly preferable.

[0079] These elastomer particles can be prepared by using a commonlyused method such as an emulsion polymerization. The emulsionpolymerization can be carried by several different methods, for example,(i) polymerizing all the monomer component in one reaction; (ii)polymerizing part of a monomer component first, then continuously orintermittently adding the remaining part of the monomer component topolymerize; (iii) polymerizing a monomer component while continuouslyadding the monomer component during polymerization; or (iv) polymerizinga monomer component by using seed particles.

[0080] An average particle diameter of the elastomer particles thusobtained is 10-700 nm. If the elastomer particles having an averageparticle diameter of less than 10 nm are used, not only the resultingthree-dimensional objects may exhibit decreased impact resistance butalso productivity and accuracy of fabrication of these objects may beadversely affected by increased viscosity of the resin composition. Onthe other hand, if the elastomer particles having an average particlediameter of more than 700 nm are used, the surface of the resultingthree-dimensional object may be rough or inaccurate fabrication mayresult.

[0081] As examples of commercially available products of thesecore-shell elastomer particles, Reginous Bond RKB (manufactured byReginous Chemical Industries Co., Ltd.), Techno MBS-61, MBS-69(manufactured by Techno Polymer Co., Ltd.), and the like can be given.

[0082] These elastomer particles can be used either individually or incombinations of two or more as the component (F).

[0083] When elastomer particles are employed the proportion of thecomponent (F) used in the photocurable resin composition of the presentinvention is usually, relative to the total weight of the composition,1-35 wt %, more preferably 3-30 wt %, and even more preferably 5-20 wt%. If the proportion is too small, the resulting three-dimensionalobjects may exhibit decreased impact resistance. On the other hand, ifthe proportion is too large, the resulting objects may exhibit lowaccuracy of fabrication.

(Optionally) Epoxy-Branched Alicyclic Compound (G)

[0084] The photocurable resin compositions of the present invention mayoptionally employ a further type of cationically polymerizable compound(herein referred to as “component (G)”). The cationically polymerizablecompound (G) used in the photocurable resin composition of the presentinvention includes alicyclic compounds wherein at least one epoxycontaining group is bound to the alicyclic group through a singlecarbon-carbon bond(herein referred to as “an epoxy-branched alicycliccompound”). Preferably, the attaching carbon from the epoxy containinggroup is one of the carbons bound to the oxygen atom forming the epoxygroup. More preferably, the attached epoxy containing group includes a1,2-epoxy wherein the oxygen bridges the terminal carbon and theimmediately adjacent carbon attached thereto, one of which I attached toa carbon from the alicyclic ring. Most preferably, the epoxy group is anepoxyethyl group.

[0085] The alicyclic group of the alicyclic compound is furtherpreferably bound, via an oxygen atom link, to a residual group of anorganic compound having a valency of from 1-100, preferably from 2-50,and more preferably from 2-30. Typically, the average valency is between1.6 and 100, preferably, between 1.8 and 50. Preferably, the alicycliccompound will comprise at least 1 epoxy-branched alicyclic group andmore preferably at least 2 epoxy-branched alicyclic groups bound via abivalent oxygen to the organic compound residue.

[0086] The precursor compound for the organic residue include, forexample, alcohols, phenols, carboxylic acids, amines, thiols, and thelike can be given. As examples of the alcohols, monohydric andpolyhydric alcohols, for example, aliphatic alcohols such as methanol,ethanol, propanol, butanol, pentanol, hexanol, and octanol, aromaticalcohols such as benzyl alcohol, and polyhydric alcohols such asethylene glycol, diethylene glycol, triethylene glycol, polyethyleneglycol, propylene glycol, dipropylene glycol, 1,3-butanediol,1,4-butanediol, pentane diol, 1,6-hexanediol, neopentyl glycol,neopentyl glycol oxypivalate, cyclohexanedimethanol, glycerol,diglycerol, polyglycerol, trimethylolpropane, trimethylolethane,pentaerythritol, and dipentaerythritol can be given.

[0087] As examples of the phenols, phenol, cresol, catechol, pyrogallol,hydroquinone, hydroquinone monomethyl ether, bisphenol A, bisphenol F,4,4′-dihydroxybenzophenone, bisphenol S, phenol resin, and cresolnovolak resin can be given.

[0088] As examples of the carboxylic acids, formic acid, acetic acid,propionic acid, butyric acid, fatty acid of animals and plants, fumaricacid, maleic acid, adipic acid, dodecanoic diacid, trimellitic acid,pyromellitic acid, polyacrytic acid, phthalic acid, isophthalic acid,and terephthalic acid can be given. A compound having both hydroxylgroup and carboxylic acid such as lactic acid, citric acid, andoxycaproic acid can also be given as examples.

[0089] Examples of the amines include methylamine, ethylamine,propylamine, butylamine, pentylamine, hexylamine, cyclohexylamine,octylamine, dodecylamine, 4,4′-diaminodiphenylmethane,isophoronediamine, xylenediamine, diethylenetriamine,triethylenetetramine, ethanolamine, and the like.

[0090] Examples of the thiols include mercaptans such asmethylmercaptan, ethylmercaptan, propylmercaptan, and phenylmercaptan,mercaptopropionic acid or polyhydric alcohol esters of mercaptopropionicacid, for example, ethylene glycol dimercaptopropionate,trimethylolpropane trimercaptopropionate, and pentaerythritolpentamercaptopropionate, and the like.

[0091] As examples of the other precursor compounds, polyvinyl alcohol,partial hydrolysis product of polyvinyl acetate, starch, cellulose,cellulose acetate, cellulose acetate butyrate, hydroxyethyl cellulose,acrylic polyol resin, styrene-allyl alcohol copolymer resin,styrene-maleic acid copolymer resin, alkyd resin, polyester polyolresin, polyester carboxylic acid resin, polycaprolactone polyol resin,polypropylene polyol, polytetramethylene glycol, and the like can begiven.

[0092] The precursor organic compounds may contain an unsaturated doublebond in the skeleton. Specific examples of such compounds include allylalcohol, acrylic acid, methacrylic acid, and the like.

[0093] Preferably, the residual organic group will be linked via an oxygroup to at least one, preferably at least two, epoxyalkyl-branchedcycloalkyl (or epoxyalkylcycloalkyl) groups. More preferably, theepoxyalkylcycloalkyl group will include those wherein the cycloalkylgroup is additionally oxy substituted, preferably hydroxy substituted,which may be referred to as an oxy-substituted (epoxyalkyl-branched)cycloalkyl. Preferably, the alkyl groups include lower alkyls comprisingeight or less carbon atoms. Preferably, the epoxyalkyl will comprise 2carbon atoms and the cycloalkyl will comprise from 5 to 6 carbon atoms.Preferred epoxyalkyl-branched cycloalkyl groups includehydroxyepoxyethylcyclohexyl groups, for example, a1-hydroxy-3-(1,2-epoxyethyl)cyclohexyl group wherein epoxy-branchedalicyclic compounds having a [(1,2-epoxyethyl)cyclohexylene]oxy group ata terminal being particularly preferred.

[0094] The molecular weight of the epoxy-branched alicyclic compound (G)is between 120 and 10,000, preferably between 150 and 5,000, morepreferably between 180 and 2,000.

[0095] Suitable epoxy-branched alicyclic compounds (G) include, forexample, those derived from trimethylolpropane, etherified with(a+b+c)1-hydroxy-3-(1,2-epoxyethyl)cyclohexyl groups, wherein a, b and care integers from 0-15 individually, provided that a+b+c=15, andcompounds derived from dipentaerythritol etherified with (a+b+c+d+e+f)epoxy-branched 1-hydroxy-cyclohexyl groups can be given, wherein theepoxy group includes 1,2-epoxyethyl and a, b, c, d, e, and f areintegers from 0-18, provided that a+b+c+d+e+f=18, and compounds derivedfrom pentaerythritol etherified with (a+b+c+d) epoxy-branched1-hydroxycyclohexyl groups can be given wherein a, b, c and d areintegers from 0-16 individually, provided that a+b+c+d=16, and compoundsderived from ethylene glycol etherified with (a+b) epoxy-branched1-hydroxycyclohexyl groups can be given, wherein a and b are integersfrom 0-20 individually, provided that a+b=20.

[0096] Commercially available products of epoxy-branched alicycliccompounds (G) EHPE3150 (manufactured by Daicel Chemical Industries,Ltd.), as described in U.S. Pat. No. 5,827,575, the entire disclosure ofwhich is hereby incorporated by reference.

[0097] Component (G), when employed in the photofabrication compositionof the present invention, may include a single type of theepoxy-branched alicyclic compound or combinations of two or more.

[0098] The proportion of the epoxy-branched alicyclic compound (G) usedin the photocurable resin composition of the present invention isusually, relative to the total weight of the composition, 2-45 wt %,preferably 5-40 wt %, and particularly preferably 10-35 wt %. If theproportion is too small, heat resistance and fabrication of theresulting three-dimensional objects are insufficient. On the other hand,if the proportion is too large, increased viscosity of the resincomposition gives rise to inferior fabrication of the resulting objects.

[0099] Additional Optional component

[0100] The photocurable resin composition of the present invention mayadditional contain optional components such as photosensitizers(polymerization accelerator) and reactive diluents other than the aboveindispensable components (A)-(G) insofar as the effect of the presentinvention is not impaired.

[0101] As examples of photosensitizers, amine compounds such astriethanolamine, methyldiethanolamine, triethylamine, and diethylamine,thioxanethone, derivatives of thioxanethone, anthraquinone, derivativesof anthraquinone, anthracene, derivatives of anthracene, perylene,derivatives of perylene, benzophenone, benzoin isopropyl ether, and thelike can be given. As examples of reactive diluents, vinyl ethers, vinylsulfides, vinylurethanes, urethane acrylates, vinylureas, and the likecan be given.

[0102] Various additives may be added to the photocurable resincomposition for photofabrication of the present invention as otheroptional components inasmuch as the object and the effect of the presentinvention are not adversely effected. Examples of such additives includepolymers or oligomers such as epoxy resin, polyamide, polyamideimide,polyurethane, polybutadiene, polychloroprene, polyether, polyester,styrene-butadiene block copolymer, petroleum resin, xylene resin, ketoneresin, cellulose resin, fluorine-containing oligomer,silicone-containing oligomer, and polysulfide oligomer, polymerizationinhibitors such as phenothiazine and 2,6-di-t-butyl-4-methylphenol,polymerization initiation adjuvant, leveling agents, wettabilityimprovers, surfactants, plasticizers, UV absorbers, silane couplingagents, inorganic fillers, pigments, dyes, and the like.

[0103] The photocurable resin composition of the present invention canbe prepared by mixing the above components (A)-(E)and optionally (F)and/or (G) homogeneously together with any additional optionalcomponents, as required.

[0104] Viscosity of the photocurable resin composition at 25° C. ispreferably 50-2,000 cps, and more preferably 70-1,500 cps.

[0105] A cured photofabrication composition of the present inventionpreferably has high impact strength. Preferably, the cured compositionof the present invention will have an impact strength of at least 3.5Kg-cm/cm², in particular an impact strength of at least 4.0 Kg-cm/cm²,and more particularly 4.5 Kg-cm/cm⁻, as measured in accordance with theIzod Impact Strength test set forth in the Examples.

[0106] Photofabrication of Three-dimensional Objects

[0107] The above-described photocurable liquid resin composition of thepresent invention can be suitably used as a photocurable liquid resinmaterial used in the photofabrication of three-dimensional objects. Thethree-dimensional objects can be fabricated from the photocurable resincomposition of the present invention by the photofabrication process,wherein energy required for curing is provided for the composition byselective exposure to radiation such as visible rays, ultraviolet rays,and infrared rays.

[0108] There are no specific limitations to the means of selectivelyirradiating the photocurable resin composition. Examples of such meansinclude: irradiating the composition by scanning with laser beams orfocused rays converged by lenses or mirrors; irradiating the compositionwith unfocused rays via a mask having a phototransmission portion with aspecified pattern; and irradiating the composition by using aphotoconductive material consisting of bundled multiple optical fibers,wherein the composition is irradiated via specific optical fiberscorresponding to the specified pattern of the photo-conductive material.In the above means utilizing a mask, a mask which electrooptically formsa mask image consisting of a photo-transmission area and anon-phototransmission area according to a specified pattern by the sametheory as that of liquid crystal display can be used. Ifmicrofabrication or higher dimensional accuracy is required forobjective three-dimensional objects, it is preferable to employ themeans comprising scanning with laser beams having a small spot diameteras the means of selectively irradiating the composition.

[0109] The irradiated surface of the resin composition in a vessel (forexample, scanning plane of focused rays) may be the liquid surface ofthe resin composition or the surface of the boundary of the resincomposition with the wall of the vessel. In this case, the compositioncan be exposed to radiation either directly or indirectly via the wallof the vessel.

[0110] In the above-described photofabrication of three-dimensionalobjects, after a specified area of the resin composition has been cured,an objective three-dimensional shape is usually fabricated by laminatingthe cured areas by continuously or gradually moving the irradiation spot(irradiation surface) from the cured area to the uncured area. Here, theirradiation spot can be moved by, for example, moving any one of a lightsource, the vessel of the resin composition, and the cured area of theresin composition, or additionally providing the resin composition inthe vessel.

[0111] A typical example of the above photofabrication ofthree-dimensional objects will be described below. First, in a vesselequipped with a support stage arranged to optionally rise and fall, athin layer (1) of the resin composition is formed over the support stageby slightly lowering (submerging) the support stage below the liquidsurface of the resin composition. This thin layer (1) is selectivelyirradiated to form a cured solid resin layer (1). The photocurable resincomposition is provided over this cured resin layer (1) to form a thinlayer (2). This thin layer (2) is then selectively irradiated to form anew cured resin layer (2) integrally laminated over the cured resinlayer (1). By repeating this process certain times using the same ordifferent irradiated patterns, the three-dimensional object consistingof an integrally-laminated plural cured resin layer (n) can be formed.

[0112] The resulting three-dimensional object is then removed from thevessel. After the residual unreacted resin compositions remaining on thesurface are removed, the object is optionally washed. As washing agents,alcohol organic solvents such as isopropyl alcohol and ethyl alcohol,ketone organic solvents such as acetone, ethyl acetate, and methyl ethylketone, aliphatic organic solvents represented by terpenes, and alow-viscosity heat-curable or photo-curable resin can be given.

[0113] If three-dimensional objects having a smooth surface arerequired, it is preferable to wash the objects using the aboveheat-curable or photo-curable resin. In this case, in accordance withthe types of curable resins used for washing the object, postcuring byusing heat- or photo-irradiation may be required. In addition, since notonly the resins on the surface of the object but also the unreactedresin compositions remaining inside the three-dimensional objects can becured by the postcure, it is also preferable to carry out the postcureafter the objects are washed with the organic solvents.

[0114] The three-dimensional objects thus obtained exhibit excellentmechanical strength, high dimensional accuracy, and superior heatresistance. Moreover, said three-dimensional objects excel in formstability and physical stability, whereby the objects exhibit superiorimpact resistance and higher folding endurance when used as prototypesfor mechanical parts.

[0115] Furthermore, in order to improve surface hardness and heatresistance of the three-dimensional objects, it is preferable to coatthe surface of the objects with heatcurable or photocurable hard coatingmaterials after washing the object. As these hard coating materials,organic coating materials such as acrylic resin, epoxy resin, andsilicone resin or inorganic hard coating materials can be used. Thesehard coating materials can be used either individually or incombinations of two or more.

[0116] Utility

[0117] As described above, the composition of the present invention canbe suitably used for photofabrication of three-dimensional objects.Moreover, owing to excellent mechanical strength of the resulting curedproduct, the composition of the present invention is useful as a coatingmaterial for plastics, various films, wood, ceramic wares, glass,communications quartz fibers, papers, metals, cans for drink, fibers,and the like, a resin for photofabrication of three-dimensional objects,sealing agents or adhesives for semi-conductor devices, underfillingagents, adhesives for optical materials, printing board materials, andthe like.

EXAMPLES

[0118] The present invention will now be described in detail by way ofexamples, which should not be construed as limiting the presentinvention.

Example 1

[0119] According to the formulations of Table 1, a vessel equipped witha stirrer was charged with 30 parts by weight of3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate “UVR-6110”(manufactured by Union Carbide Corp.), 5 parts by weight ofbis(3,4-epoxycyclohexylmethyl)adipate “UVR-6199” (manufactured by UnionCarbide Corp.), 3 parts by weight of 1,6-hexanediol diglycidyl ether“Epolite 1600” (manufactured by Kyoeisha Chemical Co., Ltd.), 2 parts byweight of triarylsulfoniumhexafluoroantimonate “UVI-6974” (manufacturedby Union Carbide Corp.), 25 parts by weight of trimethylolpropanetriacrylate “Viscoat 295” (manufactured by Osaka Organic ChemicalIndustry Co., Ltd.), 4 parts by weight of 1-hydroxycyclohexylphenylketone “Irgacure 184” (manufactured by Ciba Specialty Chemicals Co.,Ltd.), 15 parts by weight of PO-modified glycerol “Sunnix GP-400”(manufactured by Sanyo Chemical Industries, Ltd.), and 16 parts byweight of core-shell elastomer particles (core: partially crosslinkedstyrene/butadiene copolymer, shell: methyl methacrylate/glycidylmethacrylate) having an average particle diameter of 50 nm “Reginas BondRKB” (manufactured by Reginous Chemical Industries Co., Ltd.). Themixture was stirred for three hours at 60° C. to obtain a liquidcomposition (the resin composition of the present invention). Viscosityof the resulting liquid composition at 25° C. measured by using aBrookfield type viscometer was 820 cps.

Examples 2-7

[0120] Liquid compositions (the photocurable resin compositions of thepresent invention) were obtained in the same manner as in Example 1except for changing the formulations of components (A)-(F) as shown inTable 1. Viscosity of each resulting liquid composition at 25° C.measured by using a Brookfield type viscometer is shown in Table 1.

Comparative Examples 1-2

[0121] Liquid compositions (photocurable resin compositions forcomparison) were obtained in the same manner as in Example 1 except forchanging the formulations of each component as shown in Table 1.Viscosity of each resulting liquid composition at 25° C. measured byusing a Brookfield type viscometer is shown in Table 1. TABLE 1Comparative Examples Examples 1 2 3 4 5 6 7 1 23,4-Epoxycyclohexylmethyl-3′,4′-epoxycyclohexane 30 30 30 25 27 25 27 —43 carboxylate (component (A))¹⁾ Bis(3,4-epoxycyclohexylmethyl)adipate(component (A))²⁾ 5 10 25 30 35 30 25 — 25 1,6-Hexanediol diglycidylether (component (A))³⁾ 3 5 10 15 15 — — — 10 Neopentylglycol diglycidylether (component (A))⁴⁾ — — — — — 15 10 — — Triarylsulfoniumhexafluoroantimonate (component (B))⁵⁾ 2 2 2 2 2 2 2 2 2 Trimethylolpropanetriacrylate (component (C))⁶⁾ 25 22 13 11 7 11 13 35 —1-Hydroxycyclohexyl phenyl ketone (component (D))⁷⁾ 4 4 2 2 2 2 2 4 2PO-modified glycerol (component E))⁸⁾ 15 12 10 9 7 9 13 34 10 Particleshaving an average particle diameter of 50 nm — — — — — 6 — — — (core:partially crosslinked styrene/butadiene copolymer, shell: methylmethacrylate/glycidyl methacrylate) (component (F))⁹⁾ Particles havingan average particle diameter of 200 nm 16 15 8 6 5 — — 25 8 (core:partially crosslinked styrene/butadiene copolymer, shell: methylmethacrylate/glycidyl methacrylate) (component (F))¹⁰⁾ Particles havingan average particle diameter of 200 nm — — — — — — 8 — — (core:partially crosslinked styrene/isoprene copolymer, shell: methylmethacrylate/glycidyl methacrylate) (component (F))¹⁰⁾ Viscosity (cps/°C.) 820 780 640 500 520 510 590 5500 720

[0122] As shown in Table 1, the viscosity of the resin compositions ofExamples 1-7 were found to be suitable for the photofabrication ofthree-dimensional objects.

[0123] Evaluation of Photocurable Resin Composition

[0124] Each photocurable resin composition obtained in Examples 1-7 andComparative Examples 1-2 was cured by using an Ar laser. Curability ofthese compositions were evaluated according to the method describedbelow. The results are shown in Table 2. A modulus of elasticity, itsvariation with time, and deformation with time of the resulting curedproducts were measured by using a method described below. The resultswere shown in Table 2. Moreover, Izod impact strength and foldingendurance of the cured products were measured by using a methoddescribed below. The results are shown in Table 2.

[0125] Evaluation of Curability by Ar Laser

[0126] A minimum energy value at which the resin compositions cured wasmeasured by selectively irradiating the photocurable resin compositionswith a laser beam. In this measurement, a photofabrication apparatus“Solid Creator JSC-2000” (manufactured by SONY CORP.) equipped with anAr ion laser (wavelength: 351 nm, 365 nm) as a light source was usedunder the following conditions: laser spot diameter at the irradiatedsurface (liquid surface): 200 μm; laser power: 100 mW; scanning speed:from 100 mm/second to 1,000 mm/second. A resin exhibiting a smallerminimum energy value was determined as a resin having higher curability.According to the minimum energy values, curability of the resincompositions obtained in Examples and Comparative Examples was rated asexcellent, good, or bad.

[0127] Measurement of Modulus of Elasticity, Transparency and ItsVariation With Time

[0128] (1) Preparation of test specimen

[0129] The compositions were applied on a glass plate using anapplicator to form a coating film with a thickness of 200 μm. Thesurface of the coating film was irradiated with ultraviolet rays at adose of 0.5 J/cm² using a conveyer curing apparatus equipped with ametal halide lamp to prepare a semi-cured resin film. The semi-curedresin film peeled from a glass plate was put on a releasable paper. Thesemi-cured resin film was then irradiated with ultraviolet rays at adose of 0.5 J/cm² to the surface opposite to the first irradiatedsurface to form a cured resin film.

[0130] The cured resin film thus obtained was allowed to stand under thefollowing conditions to prepare test specimens 1 and 2.

[0131] Test specimen 1: Conditioned at a constant temperature of 23° C.and a relative humidity of 50% for 24 hours.

[0132] Test specimen 2: Conditioned at a constant temperature of 23° C.and a relative humidity of 50% for 30 days.

[0133] (2) Measurement

[0134] Transparency

[0135] Transparency of the test specimen 1 was evaluated with the nakedeye.

[0136] Modulus of Elasticity A modulus of elasticity (drawing speed: 1mm/min, bench mark distance: 25 mm) of each test specimen 1 (formeasurement of initial value) and 2 (for measurement of variation withtime) was measured at a constant temperature of 23° C. and a relativehumidity of 50%.

[0137] Deformation With Time

[0138] (1) Preparation of test specimen

[0139] A cured resin layer (thickness: 0.20 mm) was formed byselectively irradiating the photocurable resin compositions with a laserbeam using Solid Creator JSC-2000. The surface(liquid surface) wasirradiated using a laser beam with a power of 100 mW at a scanning speedso that cure depth of each composition was 0.3 mm. By repeating thisstep, a measurement model (hereinafter called “warping model”) as shownin FIG. 1 was formed. This warping model was then removed from thephotofabrication apparatus. The resin composition adhering to thesurface of the warping model was wiped off and excess resin compositionwas removed from the model by washing with a terpene solvent.

[0140] (2) Measurement

[0141] As shown in FIG. 2, a leg 11 of the resulting three-dimensionalwarping model 10 was fixed to a horizontal stand 20 as shown in FIG. 2.A distance (uplifting) between the horizontal stand 20 and the bottomend of a distal leg 12 was determined as warping (initial value). Thewarping model was then conditioned at a constant temperature of 23° C.and a relative humidity of 50% for 30 days. The warping amount of thiswarping model was measured in the same manner as described above. Thedeformation with time of the compositions was determined by comparingthe newly measured value with the initial value and rated as excellent,good, or bad in the order of the increasing warping amount.

[0142] Measurement of Impact Strength

[0143] (1) Preparation of test specimen

[0144] A cured resin layer (thickness: 0.20 mm) was formed byselectively irradiating the photocurable resin composition with a laserbeam using Solid Creator JSC-2000. The surface(liquid surface) wasirradiated using a laser beam with a power of 100 mW at a scanning speedso that cure depth of each composition was 0.3 mm. By repeating thisstep, test specimens according to JIS K7110 were formed.

[0145] (2) Measurement

[0146] The test specimens were conditioned at a constant temperature of23° C. and a relative humidity of 50% for about 24 hours. Izod impactstrength of the test specimens was measured according to JIS K7110.

[0147] Test of Folding Endurance

[0148] (1) Preparation of test specimen

[0149] The compositions were applied on a glass plate using anapplicator to form a coating film with a thickness of 200 μm. Thesurface of the coating film was irradiated with ultraviolet rays at adose of 0.5 J/cm² using a conveyer curing apparatus equipped with ametal halide lamp to prepare a semi-cured resin film. The semi-curedresin film peeled from a glass plate was put on a released paper. Theopposite surface of the first irradiated side of the semi-cured resinfilm was then irradiated with ultraviolet rays at a dose of 0.5 J/cm² toform a cured resin film.

[0150] (2) Measurement

[0151] The test specimen was conditioned at a constant temperature of23° C. and relative humidity of 50% for about 24 hours. The testspecimen was repeatedly folded at 60 times per second with a constantload of 100 g using an MIT folding endurance tester. Folding enduranceof test specimens was evaluated by the number of times of the testspecimen was folded before the test specimen breaks. In the case wherethe number was 30 or more the result was rated as good, in the casewhere the number was less than 30 the result was rated as bad.

[0152] Evaluation of Accuracy of Fabrication

[0153] Accuracy of fabrication of three-dimensional objects wasevaluated by measuring the dimensions of the three-dimensional objectsformed from each liquid resin.

[0154] (1) Formation of three-dimensional object

[0155] H-shaped three-dimensional objects as shown in FIG. 3 were formedby using Solid Creator JCS-2000 according to the following conditions.

[0156] These three-dimensional objects were conditioned at a constanttemperature of 23° C. and under relative humidity of 50% for about 24hours.

[0157] Fabrication Conditions

[0158] The three-dimensional objects were formed under the sameconditions as in the above-described preparation of the test specimensfor evaluation of deformation with time (laser beam intensity at theliquid surface: 100 mW, scanning speed: an optimum scanning speed atwhich cure depths of each composition were 0.30 mm, thickness of curedresin layer: 0.2 mm).

[0159] (2) Measurement of dimensional accuracy of three-dimensionalobject

[0160] Dimensions A, B, and C, which are shown in FIG. 3, of theresulting three-dimensional objects were measured by using a 0.01 mmgraduated caliper. The dimensional deviations of A, B, and C weredetermined according to the following formulas (I) and (II).

Dimensional difference between A and B=(A−B)  (I)

Dimensional difference between C and B=(C−B)  (II)

[0161] The results of evaluation were rated as follows.

[0162] absolute values of dimensional differences both between A and Band between C and B were less than 0.1 mm: ⊙

[0163] one of the absolute values of dimensional differences between Aand B and between C and B was less than 0.1 mm and the other was between0.1 and 0.19 mm: ◯

[0164] absolute values of dimensional differences both between—A and Band between C and B were between 0.1 and 0.19 mm: Δ

[0165] one of the absolute values of dimensional differences between Aand B and between C and B was 0.2 mm or more or no three-dimensionalobject was formed: X TABLE 2 Comparative Examples Examples 1 2 3 4 5 6 71 2 Curability Excellent Excellent Excellent Excellent ExcellentExcellent Excellent Bad Bad Modulus of elasticity (after 24 hours) 158160 180 175 180 175 180 — 190 (after 30 days) 154 156 178 170 175 170174 — 182 Accuracy of ◯ ◯ ⊙ ⊙ ⊙ ⊙ ⊙ X X fabrication Warping model TestTest (immediately Good Excellent Excellent Excellent Excellent ExcellentExcellent specimen specimen after test could not could not specimen wasbe formed be formed formed) (after 30 days) Good Good ExcellentExcellent Excellent Excellent Excellent Izod impact    5.2    5.1    4.6   4.8    4.7    4.6    4.8 Test Test strength specimen specimen (kg ·cm/cm²) could not could not be formed be formed Folding Good Good GoodGood Good Good Good — Good endurance

[0166] As shown in Table 2, each cured product formed from thecompositions obtained in Examples 1-7 exhibited high accuracy offabrication, high modulus of elasticity, and excellent stability withtime. Superior form stability of the cured products formed from thecompositions was evident from small deformation (warping) caused byshrinkage during curing. Moreover, these cured products exhibitedexcellent impact resistance and high folding endurance.

[0167] The cured product formed from the composition of ComparativeExample 1 in which the component (F) was not blended exhibited inferiorimpact resistance and insufficient folding endurance. Nothree-dimensional object was formed from the composition of ComparativeExample 1 in which the component (A) was not blended because ofinsufficient curability. In spite of sufficient viscosity of the curedproduct, no three-dimensional object was formed from the composition ofComparative Example 2 in which the component (C) was not blended.

Examples 8-14

[0168] According to the formulations of Table 3, transparent liquidcompositions (the photocurable resin compositions of the presentinvention) were obtained in the same manner as in Example 1 except forvarying the blend of the components (A)-(F) and adding optionalcomponents. Viscosity (25° C.) of each resulting liquid compositionmeasured by using a Brookfield type viscometer is shown in Table 3.

Comparative Examples 3-5

[0169] According to the formulations of Table 3, transparent liquidcompositions (photocurable resin compositions for comparison) wereobtained in the same manner as in Example 1 except for varying the blendof each component. Viscosity (25° C.) of each resulting liquidcomposition measured by using a Brookfield type viscometer is shown inTable 3. TABLE 3 Examples Comparative Examples 8 9 10 11 12 13 14 3 4 53,4-Epoxycyclohexylmethyl-3′,4′- — 13 25 27 34 23 23  — — 23epoxycyclohexanecarboxylate (component (A))¹⁾Bis(3,4-epoxycyclohexylmethyl)adipate 28 25 33 38 38 35 35  — — 35(component (A))²⁾ Triarylsulfonium hexafluoroantimonate  2  2  2  2  2 2 2  2 2  2 (component (B))³⁾ Trimethylolpropane triacrylate (component(C))⁴⁾ 25 20 13 13 10 — 5 51 15  — Pentaerythritol triacrylate(component (C))⁵⁾ — — — — — 13 — — — — Dipentaerythritol hexaacrylate(component (C))⁶⁾ — — — — — — 8 — — — 1-hydroxycyclohexylphenyl ketone(component (D))⁷⁾  2  2  2  2  2  2 2  2 2  2 PO-modified glycerol(component (E))⁸⁾ 12 10 10 10  8 10 10  15 10  15 Particles having anaverage particle diameter of 50 15 12  7  8 — — — — 7 — nm (core:partially cross-linked styrene/butadiene copolymer, shell: methylmethacrylate/glycidyl methacrylate) (component (F))⁹⁾ Particles havingan average particle diameter of 200 — — — —  6  7 7 15 — 15 nm (core:partially crosslinked styrene/butadiene copolymer, shell: methylmethacrylate/glycidyl methacrylate) (component (F))¹⁰⁾ Neopentylglycoldiglycidyl ether¹¹⁾ 16 16  8 — —  8 8 15 8  8 Hydrogenated bisphenol Adiglycidyl ether¹²⁾ — — — — — — — — 56  — Viscosity (cps/° C.) 750  690 520  640  620  780  890  350  2200   850 

[0170] As shown in Table 3, the compositions obtained in Examples 8-14had a suitable viscosity as the resin composition for photofabricationof three-dimensional objects and were tested, in accordance with thetests set forth above for Examples 1-7, and the results are presentedbelow in Table 4. TABLE 4 Examples Comparative Examples 8 9 10 11 12 1314 3 4 5 Curability Excel- Excel- Excel- Excel- Excel- Excel- Excel- BadBad Bad lent lent lent lent lent lent lent Transparency of Trans- Trans-Trans- Trans- Trans- Trans- Trans- Trans- Trans- Trans- cured filmparent parent parent parent parent parent parent parent parent parentModulus of elasticity (after 24 142 158 175 183 182 173 179 — — 160hours) (after 30 days) 135 153 171 179 177 165 173 — — 152 Accuracy of ◯◯ ⊙ ⊙ ⊙ ⊙ ⊙ X X X fabrication Warping model Test Test Test (immediatelyGood Excellent Excellent Excellent Excellent Excellent Excellentspecimen specimen specimen after test could not could Could specimen wasbe formed not be not be formed) formed formed (after 30 days) Good GoodExcellent Excellent Excellent Excellent Excellent Izod impact    5.2   5.0    4.6    4.7    4.7    4.6    4.6 Test Test Test strengthspecimen specimen Specimen (kg · cm/cm²) could not could could be formednot be not be formed formed Folding Good Good Good Good Good Good Good —— Good endurance

[0171] As shown in Table 4, the cured products formed from thecompositions obtained in Examples 8-14 exhibited high accuracy offabrication, high modulus of elasticity, and excellent stability withtime. Superior form stability of the cured products formed from thecompositions was evident from small deformation (warping) caused byshrinkage during curing. Moreover, these cured products exhibitedexcellent impact resistance and high folding endurance.

[0172] Comparative Example 3, in which the component (A) was not blendedand the component (C) was blended in the proportion greater thanspecified. Moreover, in the evaluation of the cured film, since the filmprepared from the composition was brittle, a modulus of elasticity andfolding endurance could not be measured.

[0173] Similar to the composition of Comparative Example 3, nothree-dimensional object was formed from the composition of ComparativeExample 4, in which the component (A) was not blended, due toinsufficient curability. A modulus of elasticity and folding endurancecould not be measured since the film prepared from the composition wasbrittle.

[0174] Although the composition of Comparative Example 5, in which thecomponent (C) was not blended, exhibited good folding endurance, nothree-dimensional object was formed from the composition because ofinferior curability.

Examples 15-18

[0175] Transparent liquid compositions (the photocurable resincompositions of the present invention) were obtained in the same manneras in Example 1 except for the alteration of the formulations of thecomponents (A)-(E) & (G) according to Table 5.

Comparative Examples 6-7

[0176] Transparent liquid compositions (photocurable resin compositionsfor comparison) were obtained in the same manner as in Example 1 exceptfor the alteration of the formulations of each component according to 5Table 5. TABLE 5 Comparative Examples Examples 15 16 17 18 6 73,4-epoxycyclohexylmethyl-3,4- 68 58 44 63  68  66epoxycyclohexanecarboxylate*¹ (component A) Triallylsulfoniumhexafluoro- 2  2  2 2 2  2 antimonate*² (component B) Trimethylolpropane 10 10 10 5— 10 triacrylate*³ (component C) 1-hydroxycyclohexylphenyl  2  2  2 2 2 2 ketone*⁴ (component D) PO-modified glycerol*⁵  8  8  8 8 8 —(component E) EHPE3150*⁶ (component G) 10 20 34 20  20  20

[0177] Evaluation of Photocurable Resin Composition

[0178] Photocurability of the photocurable resin compositions obtainedin Examples 15-18 and Comparative Examples 6-7 and heat resistance andaccuracy of fabrication of the three-dimensional objects formed fromthese compositions were evaluated according to the following evaluationmethods. The results are shown in Table 6.

[0179] Photocurability

[0180] Each composition was irradiated by using a photofabricationapparatus “Solid Creator JSC-2000” equipped with an argon ion laser(wavelength: 351 nm, 365 nm) (manufactured by SONY CORP.) as a lightsource. The laser beam was irradiated so that the intensity of the laserbeam was 100 mW at the liquid surface while altering the scanning speed.The scanning speed when the thickness of the cured layer (hereinaftercalled “cure depth”) was 0.3 mm (this speed is referred to as “optimumscanning speed”) was determined. Evaluation of photocurability of thecompositions was as follows.

[0181] optimum scanning speed was 20 cm/second or more: “◯”

[0182] optimum scanning speed was 5-20 cm/second: “Δ”

[0183] optimum scanning speed was 5 cm/second or less or cured layer wasnot formed: “X”

[0184] Heat-deformation Temperature

[0185] Three-dimensional objects (length: 120 mm, width: 11 mm,thickness: 4 mm) were formed from each composition by using the abovephotofabrication apparatus according to the following conditions (1)-(3)

[0186] (1) intensity of laser beam at the liquid surface: 100 mW

[0187] (2) scanning speed: optimum scanning speed at which the curedepth of each composition was 0.3 mm

[0188] (3) thickness of cured resin layer: 0.2 mm

[0189] The resin compositions adhering to the surface of the resultingthree-dimensional objects were wiped off and the objects were washedwith a solvent. The objects were then annealed using a heating oven forabout two hours at 100° C. to prepare test specimens used for measuringthe heat-deformation temperature.

[0190] The heat-deformation temperatures of the test specimens thusprepared were measured according to JIS K7207 A.

[0191] Evaluation of Accuracy of Fabrication

[0192] As discussed above with respect to Examples 1-14. As shown inTable 6, the resin compositions obtained in Examples 15-18 exhibitedsuperior curability, higher heat-deformation temperature, and higheraccuracy of fabrication. With respect to the resin compositions ofComparative Examples 6 and 7, low curability of the compositionsresulted in insufficient three-dimensional objects. TABLE 6 ComparativeExamples Examples 15 16 17 18 6 7 Curability ◯ ◯ ◯ ◯ X XHeat-deformation 120 128 135 125 — — temperature (° C.) Accuracy offabrication ◯ ⊙ ◯ ◯ X X

[0193] Effect of the Invention

[0194] The cured product formed from the photocurable resin compositionof the present invention exhibits small variation of mechanicalproperties with time, small deformation with time (warping), increasedmechanical strength, high dimensional accuracy, and superior heatresistance. Said cured product can be used as three-dimensional objects,for example, a prototype of mechanical parts to which superior toughnesssuch as high impact resistance and excellent folding endurance isrequired.

What is claimed is:
 1. A photocurable resin composition comprising: (A)a cationically polymerizable organic compound; (B) a cationicphotopolymerization initiator; (C) an ethylenically unsaturated monomer;(D) a radical photopolymerization initiator; and (E) a polyol.
 2. Thephotocurable resin composition according to claim 1, wherein thecomposition comprises, relative to the total weight of the composition,20-85 wt % component (A), 5-45 wt % component (C), and 5-35 wt %component (E).
 3. A photocurable resin composition according to any oneof claims 1-2, wherein said component (A) comprises at least onecompound having two or more alicyclic epoxy groups.
 4. A photocurableresin composition according to any one of claims 1-3, wherein component(C) comprises at least one polyfunctional ethylencially unsaturatedmonomer.
 5. A photocurable resin composition according to any one ofclaims 1-4, wherein component (E) comprises at least one polyetherpolyol having 3-6 hydroxyl groups.
 6. The photocurable resin compositionaccording to claims 1-5, wherein said composition further compriseselastomer particles.
 7. The photocurable resin composition according toclaim 6, wherein said elastomer particles have an average particlediameter of 10-700 nm.
 8. A photocurable resin composition according toany one of claims 6-7, wherein the elastomer particles includecore-shell particles.
 9. A photocurable resin composition according toany one of claims 6-8, wherein the elastomer particles having a basecomponent including polybutadiene, polyisoprene, styrene/butadienecopolymer, styrene/isoprene copolymer, ethylene/propylene copolymer,ethylene/olefin copolymer, ethylene/olefin/polyene copolymer, acrylicrubber, butadiene/(meth)acrylate copolymer, styrene/butadiene blockcopolymer, or styrene/isoprene block copolymer.
 10. A photocurable resincomposition according to any one of claims 6-9, wherein the elastomerparticles include at least one core-shell particle having a partiallycrosslinked core comprising polybutadiene, polyisoprene,styrene/butadiene copolymer, styrene/isoprene copolymer,butadiene/(meth)acrylate copolymer, styrene/butadiene block copolymer,or styrene/isoprene block copolymer; and a shell comprising a methylmethacrylate polymer, methyl methacrylate/glycidyl copolymer, ormethacrylate copolymer.
 11. A photocurable resin composition accordingto any one of claims 1-10, wherein said composition further comprises anepoxy-branched alicyclic compound (G).
 12. A photocurable resincomposition according to claim 11, wherein said epoxy-branched alicycliccompound (G) comprises at least 2 epoxy-branched alicyclic groups.
 13. Aphotocurable resin composition according to any one of claims 11-12,wherein said epoxy-branched alicyclic compound (G) comprises anepoxyethyl group.
 14. A photocurable resin composition according to anyone of claims 11-13, wherein said epoxy-branched alicyclic compound (G)comprises a residue of an organic compound having a valency of from1-100.
 15. A photocurable resin composition according to any one ofclaims 11-14, wherein said epoxy-branched alicyclic compound (G)comprises a residue of an organic compound linked via an oxy group to atleast one epoxyalkyl-branched cycloalkyl group.
 16. A photocurable resincomposition according to any one of claims 11-15, wherein saidepoxy-branched alicyclic compound (G) comprises an epoxyalkyl-branchedcycloalkyl group that is hydroxy substituted.
 17. A photocurable resincomposition according to any one of claims 11-16, wherein saidepoxy-branched alicyclic compound (G) includes ahydroxyepoxyethylcyclohexyl group.
 18. A photocurable resin compositionaccording to any one of claims 11-17, wherein said epoxy-branchedalicyclic compound (G) includes a 1-hydroxy-3-(1,2-epoxyethyl)cyclohexylgroup.
 19. A process for photo-fabricating a three-dimensional objectcomprising: selectively curing a photo-curable resin according to anyone of claims 1-18.
 20. A three-dimensional object formed from aphotocurable resin composition according to any one of claims 1-18, orwith a process according to claim 19.